<script setup>
import { ref } from 'vue'

const isActive = ref(true)
</script>
<template>
    <button @click="isActive = !isActive">tagger</button>
    <Transition>
        <div v-if="isActive">
            Hello world!
        </div>
    </Transition>
</template>

<style>
.v-enter-active,
.v-leave-active {
    transition: opacity 0.5s ease;
}

.v-enter-from, .v-leave-to {
    opacity: 0;
}
</style>